Problem in the game

Hello, I am Russian and so please excuse me in advance for my English. I have a few problems:
1. When you log in through your launcher to version 1.16.4 or more, I can't log in to the online game due to the fact that the button itself is black and not functioning, while if you hover over it, a sign with the inscription is displayed:check your account settings, but I can play the online game on versions 1.12.2 and below. Help please.
2. (I'm not sure if this question applies specifically to you) When you try to log in to a very popular license server, a sign with the inscription "Login error:null" is displayed"